Is Nihilism associated with depression? For me, reductionism would only not be true if genuinely Strong Emergence was the case - if small things *stopped behaving like themselves* because they somehow "knew" they were a part of a bigger thing - like if an atom of oxygen no longer behaved like oxygen atoms normally behave once it knows it's inside a human brain, or something.
As far as I can tell, there's never been any experimental evidence that small things behave fundamentally differently based on things like this. Molecules behave like they behave, if they're in a brain or not, if they're part of a human or not. Small things *are not aware* that they're part of some bigger thing, and so they just do the things small things do. I don't see any indication that most experts in the physical sciences disagree with this, but I do see indications that many do explicitly agree.
If they did, I would be going back to the drawing board myself. I care what experts think, and if it somehow WERE true unambiguously that all physicists said "strong emergence is the case, we have these scenarios where we've seen small things that stop behaving like they normally do because of this bigger thing they're a part of", then... you know, I would care about that. I care what experts think.